Hello MACKY
Keep in mind HDMI is not High Definition!
HDMI is an interconnect that carries a Digital Video plus Stereo or Multi Channel audio signal - the video signal can be Standard Definition, Extended Definition or High Definition.
Currently some sources have the ability to up-convert Standard Definition discs to a High Definition resolution - though its not the same as a True High Definition source.
Some implementations of HDMI are very good - some not.
With your projector your 'limited' to Inputting High Definition sources via its Analogue YUV inputs - you don't have HDMI on a PT-AE100.
With an Analogue High Definition source (say D-VHS) you'll see a fair old improvement over a Standard Definition DVD.
There are very few True HD sources around as yet and the ones on the horizon will mostly require that you have an HDMI Input on your projector and full signal compatibility with 720P and 1080i at 50 and 60Hz; though you can get around the HDMI issue with a 'converter' box (approx £300) if you stick with your Analogue only projector.
If your serious about HD then I'd suggest a new 'HD Ready' or 'HD Compatible' Projector is on your near horizon
Best regards
Joe